package com.coszero.utils.decoration

import android.graphics.Rect
import android.view.View
import androidx.recyclerview.widget.RecyclerView

/**
 * 空白分割线
 * http://blog.csdn.net/johnwcheung/article/details/54953568
 *
 * @author fujinhu
 * @date 2017/8/9
 * @version 1
 */
class SpacingItemDecoration
/**
 * @param spanCount 列数：为1时为list,只会在下方分割，<1时为网格
 * @param spacing 分割宽度 px
 * @param includeEdge 是否包括父布局边缘 true:靠近父布局的item也会留出空间，false：不留空间
 */(private val spanCount: Int, private val spacing: Int, private val includeEdge: Boolean) :
    RecyclerView.ItemDecoration() {
    override fun getItemOffsets(
        outRect: Rect,
        view: View,
        parent: RecyclerView,
        state: RecyclerView.State
    ) {
        val position: Int = parent.getChildAdapterPosition(view) // item playPosition
        val column: Int = position % spanCount // item column

        if (includeEdge) {
            outRect.left =
                spacing - column * spacing / spanCount // spacing - column * ((1f / spanCount) * spacing)
            outRect.right =
                (column + 1) * spacing / spanCount // (column + 1) * ((1f / spanCount) * spacing)

            if (position < spanCount) { // top edge
                outRect.top = spacing
            }
            outRect.bottom = spacing // item bottom
        } else {
            outRect.left = column * spacing / spanCount // column * ((1f / spanCount) * spacing)
            outRect.right =
                spacing - (column + 1) * spacing / spanCount // spacing - (column + 1) * ((1f /    spanCount) * spacing)
            if (position >= spanCount) {
                outRect.top = spacing // item top
            }
        }
    }
}
